The invention relates to microprocessor cards which are capable of performing operations on data supplied by memories associated with the microprocessor or by a terminal to which they are connected.
In a simplified manner, a microprocessor 10 (see single FIGURE) comprises a central unit 12 which communicates with a program memory 16, a data memory 18 and a memory 14 of the RAM type, RAM being the English acronym for “Random Access Memory”. This microprocessor 10 is connected to a terminal 20 by means of a link 32 and a contact pin 22.
The electrical signals applied by the terminal 20 to the contact pin 22 are analysed by the microprocessor 10 by means of a special so-called communication program recorded in the program memory 16, this communication program being adapted to the communication protocol which controls the exchanges of information between the card and the terminal in both directions.
Analysis of the electrical signals applied to the contact pin 22 constitutes a relatively lengthy task for the central unit 12, a task which mobilises a large part of the memories.
In a similar manner, the output of the information from the microprocessor 10 to the terminal 20 by means of the contact pin 22 also takes up the time of the central unit and space in the memories.
The aim of the present invention is therefore to produce a microprocessor card which does not have the aforementioned drawbacks so as to release time for the microprocessor for other tasks and to release memory capacity for these other tasks.